Donor/recipient mixed chimerism does not predict graft failure in children with beta-thalassemia given an allogeneic cord blood transplant from an HLA-identical sibling.
BACKGROUND
Donor/recipient mixed chimerism has been reported to be associated with an increased risk of graft failure in patients with beta-thalassemia given a bone marrow transplant. We investigated the relationship between the degree of mixed chimerism over time and clinical outcome of children undergoing cord blood transplantation for beta-thalassemia.


METHODS
Twenty-seven consecutive children given a cord blood transplant from a related donor were analyzed by short tandem repeat polymerase chain reaction and their chimerism results were compared with those of 79 consecutive patients who received a bone marrow transplant from either a relative (RD-BMT, n=42) or an unrelated donor (UD-BMT, n=37). Cord blood and bone marrow recipients received comparable preparative regimens.


RESULTS
All cord blood recipients engrafted and displayed mixed chimerism early after transplantation; 13/27 converted to full donor chimerism over time, while 14 maintained stable mixed chimerism; all patients are alive and transfusion-independent. Twenty-four of the 79 bone marrow-recipients (12 UD- and 12 RD-BMT) exhibited full donor chimerism at all time points examined, 4/79 (2 UD- and 2 RD-BMT) did not engraft and 51/79 (23 UD- and 28 RD-BMT) displayed mixed chimerism at the time of hematologic reconstitution. Forty of 51 bone marrow recipients with mixed chimerism converted to full donor chimerism (17 UD- and 23 RD-BMT), 3/51 maintained stable mixed chimerism (1 UD- and 2 RD-BMT), while 8/51 (5 UD- and 3 RD-BMT) progressively lost the graft, and became transfusion-dependent again.


CONCLUSIONS
Mixed chimerism is a frequent event and does not predict the occurrence of graft failure in children with beta-thalassemia given a cord blood transplant from a relative.
Lisini
Daniela
D
Oncoematologia Pediatrica, Laboratorio di Immunologia dei Trapianti, Fondazione IRCCS Policlinico San Matteo, P.le Golgi, 2, I-27100 Pavia, Italy. d.lisini@smatteo.pv.it
Zecca
Marco
M
Giorgiani
Giovanna
G
Montagna
Daniela
D
Cristantielli
Rosaria
R
Labirio
Massimo
M
Grignani
Pierangela
P
Previderè
Carlo
C
Di Cesare-Merlone
Alessandra
A
Amendola
Giovanni
G
Bergami
Elena
E
Mastronuzzi
Angela
A
Maccario
Rita
R
Locatelli
Franco
F
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D036101:Cord Blood Stem Cell Transplantation; D005260:Female; D006084:Graft Rejection / Q000175:diagnosis* / Q000276:immunology; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D007223:Infant; D008297:Male; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D035781:Siblings; D014019:Tissue Donors; D018183:Transplantation Chimera; D014184:Transplantation, Homologous; D055815:Young Adult; D017086:beta-Thalassemia / Q000628:therapy*
D006680:HLA Antigens